Topography of the post-imperative negative variation in schizophrenic patients and controls obtained from high-resolution ERP maps

The post-imperative negative variation (PINV) comprises a slow negative potential shift extending up to several seconds following a signaled taskrelevant stimulus or response. This slow negativity is particularly intriguing, since it seems to be a component of event-related potentials which is found to be larger in amplitude in schizophrenics than in healthy subjects, whereas typically, amplitudes of such components are reduced in patient groups. In the latter case, differences may be due to higher intra-individual response variability and lower signal-to-noise ratio on the part of the patients. Obviously, such an interpretation cannot explain the PINV results. Furthermore, the occurrence of a PINV seems to be reliably related to the diagnosis of a schizophrenic disorder and other severe psychopathological conditions. It can be elicited repeatedly, and measured, independent of clinical judgment, objectively as well as non-invasively. Although frequently found in schizophrenic patients, the PINV is not a specific signature of schizophrenia but is also found in patients with major depressive disorders, and sometimes also in anxiety disorders [1-3], and in patients with obses-